<!Doctype html>
<html>

<head>
    <meta charset="UTF-8">
    <title>区块放大</title>
    <style>
        * {
            margin: 0;
            padding: 0;
        }

        .container div {
            background-color: #cdd8db;
            text-align: center;
        }

        .div1 {
            width: 30%;
            height: 50%;
            line-height: 125px;
            float: left;
        }

        .div2 {
            width: 68%;
            line-height: 250px;
            float: right;
        }

        .div3 {
            float: left;
            width: 30%;
            height: 48%;
            line-height: 120px;
            margin-top: 20px;
            position: absolute;
            bottom: 0;
            left: 0;
        }
        .container {
            position: relative;
            width: 280px;
            height: 250px;
            margin: 100px auto;
        }
    </style>
    <script>
        function big(obj) {
            obj.style.border = "1px solid #000";
            obj.style.backgroundColor = '#def8c0';
            obj.style.position = "absolute";
            obj.style.zIndex = 1;
            obj.style.width = "107px"
            obj.style.height = "158px"
        }
        function small(obj) {
            obj.style.border = '1px solid #00a7f7';   //为了兼容IE，这里最好不要填空
            obj.style.backgroundColor = '';
            obj.style.width = '';
            obj.style.height = '';
        }
    </script>
</head>

<body>
    <div class="container">
        <div class="div1" id="div1" onmouseover="big(this)" onmouseout="small(this)">a</div>
        <div class="div2">b</div>
        <div class="div3">c</div>
    </div>
</body>

</html>